In current inkjet printing systems, printheads are expected to achieve long lives in proper working conditions. In order to provide good reliability some printhead cleaning and maintenance routines are needed. One of the common cleaning methods is priming, which includes forcibly extracting ink from the printhead using either a positive or negative pressure gradient.
There are a number of events that may cause an unsuccessful priming event, including but lot limited to the following:                1. the peristaltic pump is broken, or has leaks;        2. the ink tubes are broken, have leaks or are clogged by ink debris;        3. the vacuum accumulator is clogged by ink residue;        4. the actuator features that act as valves are broken;        5. the service station caps are broken and/or do not provide a good seal;        6. the printhead is clogged and ink can not flow through the nozzles; or        7. the printhead regulator does not open despite the pressure changes in the printhead.If any one of these events occurs, or a combination of such events occurs, the priming system may not be able to extract ink from the printhead and perform the cleaning routine.        
Failure to recognize that priming operations are not properly occurring can result in formation of ink deposits inside and outside the printhead, clogged printhead nozzles, damage to the printhead, and degraded print quality. These conditions can lead to increased cost of ownership and decreased customer satisfaction.